There is proposed a camera system for use in e.g. a mobile phone, mobile terminal or vehicle-mounted camera, which has a downsized and thin structure including: a wiring board mounting on a front surface thereof an image sensor (as an optical element); lower-side outer and upper-side inner holders erected on an outer peripheral region of the front surface of the wiring board; and a lens, a diaphragm and an infrared cut filter disposed in the inner holder (see, for example, Patent Document 1).
In this camera system, the image sensor is mounted in a state of being sealed from the outside by the wiring board, the outer and inner holders and the lens.
During outdoor use of the above-proposed camera system in e.g. a mobile phone, mobile terminal or vehicle-mounted camera, however, condensation or freezing may occur on a surface of the lens or infrared cut filter due to a difference between the outside air temperature and the inside ambient temperature of the camera system. In such a case, an image from the outside is intercepted by the condensation or freezing, whereby there arises a problem that an image captured by the camera system is not accurate or a problem that a part of light from the mounted light-emitting diode (optical element) is not emitted to the outside.